The ability to join two items together, without the need of a mechanical fastener, can be performed by use of an adhesive. The types of applications for adhesives are too numerous to list. In the marine industry, a product that provides a combination adhesive and sealant has been found to be particularly useful. Boat manufacturers and operators avoid using metal fasteners unless absolutely necessary due to the problem with electrolysis, which can be especially progressive in salt water. For this reason, the use of an extremely high tack polyurethane adhesive/sealant has become universally recommended for bonding and sealing of underwater thru-hull fittings, bonding of wood to fiberglass, rubrails to fiberglass, windows to fiberglass, fiberglass to fiberglass, hull-to-deck joints, electrical insulation, and so forth.
For instance, polyurethane adhesive/sealants can be used to accompany thru-hulls for raw water engine intake, air conditioner intakes, macerator in-take and out-take fittings, transducers and so on wherein placement of the material around the fitting during installation creates not only an impermeable seal, but the adhesive prevents the fitting from coming loose.
Polyurethane adhesive/sealant has incredible adhesion abilities, yet it maintains the ability to remain flexible after it cures. Unique to the polyurethane material is its ability to remain workable for up to four hours, wherein it becomes tack-free in 48 hours and completely cures within seven days. Polyurethane adhesives/sealant further remains flexible after it cures. This allows the fitting to move if need be without cracking of the fiberglass or gelcoat. One such manufacturer of adhesive, the 3M Corporation, markets the most popular brand known as 5200 adhesive/sealant.
A problem with superior holding ability of the polyurethane adhesive occurs if the material needs to be removed. For example, metal fittings that are used on a boat, especially fittings placed below the water line, are subject to electrolysis or simply wear out. In any event, eventually such thru-hulls must be replaced or a structural integrity problem arises. For this reason, thru-hulls must be replaced routinely and the superior adhesion of the polyurethane adhesive/sealant dealt with. When the polyurethane adhesive is uncured, it can be removed with a solvent such as kerosene. Once cured, no known substance is marketed for removal of the polyurethane that can be used safely by the general consumer. Without chemical softening, the adhesive must be broken out of the seal by use of a screwdriver, sharp knife, grinder, or the like tool. If not performed expertly, the gelcoat and underlying fiberglass may be marred leading to additional problems. In those instances, removal of the fitting joined by use of the polyurethane adhesive/sealant can result in a tremendous amount of damage to a vessel wherein any attempt to place a new thru-hull into the damaged area will provide a latent failure condition which could lead to sinking of the vessel.
In many instances the item that is bonded remains in good condition and need only be moved. For example, table tops in boats are typically joined by use of polyurethane adhesive. If incorrectly joined, one item may be destroyed in an attempt to separate the items. Even if separated, the remaining adhesive may be difficult to remove requiring scraping or grinding to remove the old adhesive before the new adhesive is employed.
Thus, what is lacking is a convenient means of destroying the adhesive bond on cured polyurethane adhesive/sealant without affecting the items to which the adhesive is secured to.